From Longman Dictionary of Contemporary Englishboonboon /buːn/ noun [countable usually singular] USEFULsomething that is very useful and makes your life a lot easier or better The bus service is a real boon to people in the village.
Examples from the Corpus
boon• But with careful management the carp can still be a boon to water authorities.• But I would crave a boon for myself and my successors.• For some estate agents, though, it is a boon.• Is snow an environmental boon or a menace?• It also is a great boon to vegetarians who can cook grains and dried beans in 12 minutes or less.• A recently acquired photo-copier has proved a great time-saving boon for note taking.• The law is a special boon to those, like top corporate honchos, who are due large sums of deferred compensation.• Their boon is life for ever freed from toil.Origin boon (1100-1200) Old Norse “prayer, request” 